This invention relates to gaskets having embossments of improved strength which resist flattening under compression thereby enhancing their sealing characteristics.
Gaskets are widely used for providing seals between pairs of confronting surfaces, such as between engine blocks and heads in internal combustion engines, and the like. Gaskets used in such applications must provide an effective seal between the relatively large number of interconnecting cavities carrying fluids of different types and under different pressures so that the fluids do not intermingle or leak externally. Such gaskets most frequently incorporate a metallic body and may be provided with one or more sealing embossments. Such embossments are projections provided on the body of the gasket for the purpose of providing a smaller area of contact between the gasket and the confronting surfaces in order to increase the compression force per unit area, thereby to generate a more effective seal. U.S. Pat. No. 3,352,564 to Johnson discloses a gasket having typical embossments which are formed by deforming the metal body, as around cylinder openings, so the body is deflected upwardly and downwardly from the plane of the surrounding gasket metal. An embossment made in this manner includes a raised portion or projection, and defines a corresponding indented portion or recess on the other side of the projection.
One of the problems which has been encountered with gaskets having embossments of the kind typified by those shown in the Johnson patent is that the embossments flatten under compression. When this occurs, the load which was intended to be concentrated in the zone of the embossment tends to be distributed over a much broader surface of the gasket, consequently lowering the effectiveness of the seal.